Mg-Zn-Ca 作为骨植入生物合金近年来受到广泛关注。 通过差热分析(DTA)、X射线衍射(XRD)和配备能量 色散谱仪(EDS)的扫描电子显微镜(SEM)对铸态Mg-4Zn-xCa(x=1、2、3，质量分数，%)合金的微观组织、成分和相组成进 行了精确表征。通过析氢实验测试了合金的宏观腐蚀速率，并利用动态腐蚀观察技术确定了合金中各相的腐蚀顺序；探 讨了不同Ca含量对合金相变化、相存在形式以及腐蚀机理的影响，确定了相组成、相腐蚀顺序与合金腐蚀速率之间的 内在联系。 研究结果显示合金微观腐蚀顺序为Mg2 Ca相>α-Mg基体>Ca2 Mg6 Zn3相。 当晶界仅存在Ca2 Mg6 Zn3相时， α-Mg 基体的腐蚀在到达晶界后会被Ca2 Mg6 Zn3相阻挡。 然而， 当Mg2 Ca相与Ca2 Mg6 Zn3相在晶界交替分布时，Mg2 Ca 相的优先腐蚀破坏了晶界第二相的网状结构，从而无法有效阻止α-Mg基体的腐蚀扩展，在宏观上表现为腐蚀速率更 高。 因此，Mg-4Zn-xCa 合金的微观第二相构成及其在晶界的分布形式是决定Mg-Zn-Ca合金宏观腐蚀速率差异的关键 因素。

 In recent years, considerable attention has focused on the use of Mg-Zn-Ca as a bioalloy for bone implantation. The microstructures, compositions and phases of the as-cast Mg-4Zn-xCa (x=1, 2, 3, wt.%) alloys were characterized with high precision via differential thermal analysis (DTA), X-ray diffraction (XRD) and scanning electron microscopy (SEM) with an energy dispersive spectrometer (EDS). The macroscopic corrosion rates of the three alloys were measured via hydrogen precipitation experiments, and the corrosion order of the phases in the alloys was determined via dynamic corrosion observation techniques. The intrinsic connections among the phase composition, phase corrosion order and corrosion rate of the alloys were further analysed, and the effects of different Ca contents on the phase changes, phase forms and corrosion mechanisms of the alloys were explored via energy spectrum analysis. The results demonstrate that the microscopic corrosion order of the alloy is Mg2 Ca phase > α-Mg matrix > Ca2 Mg6 Zn3 phase. In the presence of the Ca2 Mg6 Zn3 phase at the grain boundaries, corrosion of the α-Mg matrix is effectively blocked by the Ca2 Mg6 Zn3 phase. However, when the Mg2 Ca phase and the Ca2 Mg6 Zn3 phase are distributed alternately at the grain boundaries, the preferential corrosion of the Mg2 Ca phase destroys the reticulation structure of the second phase at the grain boundaries, thereby preventing the corrosion extension of the α-Mg matrix. Consequently, from a macroscopic perspective, the corrosion rate of the alloy containing the Mg2 Ca phase is higher. The microscopic composition of the second phase and its distribution at the grain boundaries are therefore identified as the key factors determining the differences in the macroscopic corrosion rates of the Mg-Zn-Ca alloys.